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Barium oxide

Barium oxide
NaCl polyhedra.png
Barium oxide.JPG
Names
Other names
Barium monoxide
Barium protoxide
Calcined baryta
Baria
Identifiers
1304-28-5 YesY
3D model (Jmol) Interactive image
ChemSpider 56180 YesY
ECHA InfoCard 100.013.753
PubChem 62392
RTECS number CQ9800000
Properties
BaO
Molar mass 153.326 g/mol
Appearance white solid
Density 5.72 g/cm3, solid
Melting point 1,923 °C (3,493 °F; 2,196 K)
Boiling point ~ 2,000 °C (3,630 °F; 2,270 K)
3.48 g/100 mL (20 °C)
90.8 g/100 mL (100 °C)
Reacts to form Ba(OH)2
Solubility soluble in ethanol, dilute mineral acids and alkalies; insoluble in acetone and liquid ammonia
-29.1·10−6 cm3/mol
Structure
cubic, cF8
Fm3m, No. 225
Octahedral
Thermochemistry
70 J·mol−1·K−1
−582 kJ·mol−1
Hazards
Safety data sheet See: data page
Harmful Xn
R-phrases R20/22
S-phrases (S2), S28
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 2: Undergoes violent chemical change at elevated temperatures and pressures, reacts violently with water, or may form explosive mixtures with water. E.g., phosphorus Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
Related compounds
Other anions
Barium hydroxide
Barium peroxide
Other cations
Calcium oxide
Strontium oxide
Supplementary data page
Refractive index (n),
Dielectric constantr), etc.
Thermodynamic
data
Phase behaviour
solid–liquid–gas
UV, IR, NMR, MS
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YesYN ?)
Infobox references

Barium oxide, BaO, is a white hygroscopic non-flammable compound. It has a cubic structure and is used in cathode ray tubes, crown glass, and catalysts. It is harmful to human skin and if swallowed in large quantity causes irritation. Excessive quantities of barium oxide may lead to death.

It is prepared by heating barium carbonate with coke, carbon black or tar or by thermal decomposition of Barium nitrate.

Barium oxide is used as a coating for hot cathodes, for example, those in cathode ray tubes. It replaced lead(II) oxide in the production of certain kinds of glass such as optical crown glass. While lead oxide raised the refractive index, it also raised the dispersive power, which barium oxide does not alter. Barium oxide also has use as an ethoxylation catalyst in the reaction of ethylene oxide and alcohols, which takes place between 150 and 200 °C.

It is also a source of pure oxygen through heat fluctuation. It readily oxidises to BaO1+x by formation of a peroxide ion. The complete peroxidation of BaO to BaO2 occurs at moderate temperatures but the increased entropy of the O2 molecule at high temperatures means that BaO2 decomposes to O2 and BaO at 1175K.

The reaction was used as a large scale method to produce oxygen before the air separation became the dominant method in the beginning of the 20th century. The method was named after its inventors the Brin process.


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